miRNAs are small regulatory RNA molecules the modulate gene expression by binding to their target mRNAs and either promoting mRNA degradation or inhibiting translation. miRNAs also circulate in plasma in association with exosomes. In the past year, we found that miRNAs can also associate with lipoproteins (ref. 2). Furthermore, we found that the content of miRNAs can vary with dyslipidemias, indicating that they can potentially serve as biomarkers for cardiovascular disease. Delivery of miRNAs by cellular uptake of exosomes has been shown to modulate gene expression. Using reconstituted HDL containing miRNAs, we were able to deliver miRNAs to cells via the SR-BI receptor and alter the expression of their target genes, which indicates that delivery of endogenous miRNAs by lipoproteins can potentially alter gene expression. Future studies will be aimed at understanding the role of both extracellular and intracellular miRNAs on lipid metabolism.